Arrests of foreign women for suspected vice-related activities have decreased steadily over the past four years.
Police statistics show that there were 5,123 arrests last year for offences such as soliciting or unlicensed prostitution, down from 5,326 arrests in 2012.
The most dramatic decrease was between 2010 and 2011, when the number of women arrested declined from 7,083 to 5,206.
Non-governmental organisations that deal with sex workers said the drop could be because Singapore is becoming a less attractive destination for sex work.
Police declined to comment on why numbers have dropped, but said they will continue to conduct regular islandwide enforcement operations against vice activities.
The Straits Times understands that the dip in arrests is not due to less enforcement.
"Singapore has become a less enticing place for prostitution," said Mr John Gee, head of research at migrant workers group Transient Workers Count Too. He said this might be due to increasing intolerance towards prostitution in residential areas.
Public uproar over prostitution in areas such as Kovan, Bedok, Marine Parade and Joo Chiat has consistently made headlines.
Mr Gee added: "Singapore wants to attract foreign tourists and residents who have high incomes, and these people want something that is more family-friendly."
Even in red-light districts like Geylang, sex workers are finding it harder to ply their trade.
Said Ms Vanessa Ho, coordinator at anti-human trafficking group Project X: "I have been to Geylang almost every night over the past year, and there have been police raids by the hour. Geylang is getting harder and harder to work in."
But she said the present number of arrests is still alarming because the figures are many times the number of licensed prostitutes in Singapore. She estimates there are 800 to 1,000 licensed prostitutes who operate out of brothels and have to go for regular health screenings.
The question is why 5,100 sex workers choose not to work quasi-legally here, she said, adding that many of of them could be victims of sex trafficking.
She said the upcoming Prevention of Human Trafficking Bill could do more to protect genuine victims, such as ensuring they will not be thrown into detention.
The Bill, which was tabled last month, will be read a second time in Parliament next week.
This article was first published on Nov 1, 2014.
Get a copy of The Straits Times or go to straitstimes.com for more stories.